Wire can be formed by running a small diameter feed wire through a liquid metal bath held in a refractory container. As the feed wire passes through the bath, liquid metal freezes onto the feed wire to produce a wire of increased diameter. Consequently, the process can be referred to as "freeze-forming."
A prior art freeze-forming process, as illustrated in FIG. 1 and further described below, has been used to make stainless steel wire, but is unsuitable for the manufacture of wire formed from a metal that will react with the refractory materials used for the molten metal container 130, the nozzle 125 and the stopper rod 122. A chemically reactive metal, in its molten state, will attack and decompose refractory materials with which it comes into contact.
A suitable substitute for the refractory container, namely a cooled, segmented, metallic crucible, is disclosed in U.S. Pat. No. 4,058,668 entitled Cold Crucible. However, this does not solve the problem of reactive metal attack on the refractory stopper rod and nozzle shown in FIG. 1. In the present invention, the stopper rod is eliminated and the refractory nozzle is replaced by a water-cooled nozzle, inside which the metal is heated. Therefore, the present invention overcomes the problems of the prior art for freezing-forming a reactive metal wire.